National Spectrum Strategy 37 GHz Spectrum Sharing Report

Developing a National Spectrum Strategy

• U.S. policymakers have long recognized the unique sharing opportunities of the Lower 37 GHz band, as well as the need to protect Federal sites, including 15 military sites, five National Aeronautics and Space Administration receiving earth station operations and two National Science Foundation sites.
• In coordination with NTIA, the FCC in 2016 adopted an Order that concluded that non-Federal fixed and mobile applications can share 37-38.6 GHz with DoD operations. The Order made the Lower 37 GHz band available for co-primary sharing, with both Federal and non-Federal users accessing the band by registering sites through a coordination mechanism.
• In 2019, the FCC established service rules addressing Federal sites for a 2020 auction in the 37 GHz band, with sharing rules for 37.0-37.6 GHz to be addressed at a later date. Among other things, the decision added one Federal site to the list of protected Federal sites in the 37 GHz band and limited future DoD access to the 37.6-38.6 GHz (Upper 37 GHz) band unless the Department could demonstrate that its operations cannot be accommodated in the Lower 37 GHz band.
• To enable an innovative sharing approach for the Lower 37 GHz band, the FCC, NTIA and DoD began discussions in 2020 on the details of a coordination mechanism. These discussions resulted in a draft sharing framework, based on first-in user rights.
• Following the release of the NSS Implementation Plan, the FCC released a 2024 Public Notice, that sought information on sharing issues in the Lower 37 GHz band, including how to accommodate various use cases through a coordination mechanism between Federal and non-Federal operators.

Use Cases

Expected uses of the Lower 37 GHz band include data-intensive applications, such as high speed, low latency 5G services. Wireless operators view this spectrum as well-suited for providing additional bandwidth, for example during large events through indoor distributed antenna deployments. Industry also sees value in the band for addressing increased demand for mobile network capacity by offloading traffic from other bands.

• Potential use cases include fixed wireless access; high-capacity backhaul; cable supplement for Internet of things (IoT) networks and augmented reality applications; and mobile or private networks that support industrial IoT, smart factories and other high-bandwidth indoor communications applications.
• Federal users, including DoD, may leverage some of this same technology, including as part of potential additional adaptations to meet mission requirements (e.g., hardening).
• Although not being proposed for any specific frequency allocation at this time, DoD is evaluating additional use cases to meet military missions, including: (1) Unmanned Systems to provide terrestrial or maritime to aeronautical mobile and potentially space to aeronautical mobile (maritime, terrestrial) unmanned systems; and (2) Wireless Power Transfer to provide a variety of capabilities currently in development by military research labs to deliver power to wireless communication systems, mobile vehicles, surface and subsurface vehicles, and other potential uses cases.

Recommendations

Based on the foregoing, we make the following recommendations for sharing between Federal and non-Federal users:

• Coordination Framework: To coordinate shared access between Federal and non-Federal users, NTIA and DoD support the use of the two-phase procedures described in the FCC Public Notice. The first phase would use simple propagation models to determine whether there are overlapping contours and permit operations to proceed in the absence of any overlap. The second phase would apply in the event of overlap between a proposed site registration and an existing site already registered in the database and would require the parties to exchange more detailed data and attempt to coordinate their operations. We expect the second phase of coordination will proceed quickly; if there is a dispute between the parties, the matter would be referred to NTIA and the FCC for resolution. This coordination framework described in the Public Notice would provide a "floor" to establish initial sharing rules. We support the potential evolution of the database to more dynamic mechanisms based on demonstrated need and available technology.
• Priority Access (37.0-37.2 GHz): DoD would retain 200 megahertz of priority access (37.0-37.2 GHz). Non-Federal entities would be permitted to access the lower 200 megahertz, with the understanding their operations may be preempted by DoD. If the contours of an existing or planned DoD system overlap with those of a deployed commercial system in the lower 200 megahertz, DoD would reserve the right to provide notice (through NTIA and the FCC) to the commercial operator that it must cease or reduce its operations to eliminate the overlap, unless the non-Federal entity is able to otherwise coordinate to the satisfaction of DoD.
• Co-equal Access (37.2-37.6 GHz): Sharing in this part of the band would be on a co-equal basis between Federal and non-Federal users. Because DoD and other Federal operations are likely to be a "second-in" use based on their longer acquisition timelines and technology development lifecycles, we support a build-out requirement for Federal users of at least 24 months from when they enter a site into the coordination portal.
• Adjacent Band Protection: A critical issue is the need to protect operations in the adjacent 36-37 GHz band. Earth Observations from environmental satellites that use this spectrum serve in a variety of purposes, including water and precipitation detection, and are leveraged extensively by DoD. NTIA recommends an administrative change to update the U.S. footnotes to reflect a resolution from the World Radiocommunication Conference in 2019, which was designed to address the interference risk to passive space-based sensors below 37 GHz that may accompany expanded fixed and mobile wireless deployments above 37 GHz.

Conclusion

The Lower 37 GHz band presents a unique opportunity to advance what the NSS describes as the "potential expanded governmental and non-governmental use for an array of advanced, next-generation applications and services." An initial coordination framework based on "first-in" user rights that protects "second in" access will advance the long-standing vision for this co-primary band of co-equal access for Federal and non-Federal users. Further, this innovative sharing framework can be made possible by ensuring that adjacent band protections for passive space-based sensors are addressed in accordance with the recommendations to address the interference risk of new deployments of in the Lower 37 GHz band. We look forward to next steps in implementing coexistence measures that advance a range of sharing innovations for this spectrum.

Table of Figures

Figure 1 - Excerpt of Table of Frequency Allocations, U.S. Table

Figure 2 - 15 Protected Military Sites

Figure 3 - Six protected military sites under Part 30 (China Lake, Fort Irwin, Edwards AFB, San Diego, Calif.; Yuma Proving Ground, Fort Huachuca, Ariz.)

Figure 4 - Four protected military sites under Part 30 (Fort Carson, Colo.; Fort Hood and Fort Bliss, Texas; White Sands Missile Range, N.M.)

Figure 5 - Examples of DoD Sites for 5G Experimentation

Figure 6 - WRC-19, Resolution 243 Table 1

Figure 7 - One Example of an Out-of-Band Emission Mask Consistent with Resolution 243

Figure 8 - Additional Out-of-Band Emission Masks Consistent with Resolution 243

Office

Office of Spectrum Management (OSM)

Program

National Spectrum Strategy